A method for producing cumene by the reaction between benzene and propylene, a method for producing cumene hydroperoxide by the oxidation of cumene, and a method for producing phenol and acetone by the acidolysis of cumene hydroperoxide are known. A combined method of these reactions is a method for producing phenol generally referred to as the cumene process and is a mainstream method for producing phenol.
One of the characteristics of the cumene process is the production of acetone as a by-product. This is advantageous when acetone is desired. However, when acetone is surplus to requirements, an unfavorable price difference between acetone and the raw material propylene causes a serious drawback.
In order to improve the price relationship between the raw material olefin and a by-product ketone, for example, a method has been proposed in which the oxidation and acidolysis of secondary butylbenzene produced from n-butene and benzene yields phenol and methyl ethyl ketone (see, for example, Patent Literatures 1 and 2). However, the selectivity for the target secondary butylbenzene hydroperoxide in the oxidation of secondary butylbenzene in this method is only approximately 80%, and 15% or more acetophenone is produced as a by-product. Thus, this method for producing phenol has a smaller yield than the cumene process.
Another method has been proposed in which the oxidation and acidolysis of cyclohexylbenzene produced from cyclohexene and benzene yields phenol and cyclohexanone. This method involves the dehydrogenation of cyclohexanone into phenol, thereby formally avoiding the production of a by-product ketone. However, the method has a still lower yield in the oxidation reaction of cyclohexylbenzene into the target cyclohexylbenzene hydroperoxide. Thus, the method is of low industrial value (see, for example, Patent Literature 3).
Regarding the cumene process having the highest yield in the oxidation and acidolysis, in order to avoid the problem of the raw material propylene and the by-product acetone while securing the advantages of the cumene process, a method has been proposed in which the by-product acetone is used as a raw material for the cumene process by various methods.
Acetone can be easily hydrogenated to produce isopropanol. The dehydration reaction of isopropanol yields propylene, which is then reacted with benzene to yield cumene. Thus, the process proposed uses acetone as a raw material for the cumene process (see, for example, Patent Literature 4).
Still another method has been proposed in which isopropanol produced by the hydrogenation of acetone is directly reacted with benzene to produce cumene (see, for example, Patent Literature 5 and Patent Literature 6).
A process method has been proposed in which acetone is converted into isopropanol, isopropanol is reacted with benzene to produce cumene, and cumene is used to produce phenol (see, for example, Patent Literature 7).
Still another method has been proposed in which acetone is directly reacted with benzene in the presence of hydrogen (see, for example, Patent Literature 8).
The alkylation of benzene with isopropanol or via isopropanol in a reaction system produces water. Since water reduces the acid strength of an acid catalyst, which is an alkylation catalyst (see, for example, Patent Literature 9), the acid catalyst is required in large quantities. This is a great problem in commercialization.